::before/::after are not features for invalidation.

We store a flag for finding ::before or ::after in
InvalidationSetFeatures, yet they are not added as features to
invalidation sets. That means we need to handle *::before as a universal
selector and cause subtree invalidations.

R=ericwilligers@chromium.org
BUG=581675

Review URL: https://codereview.chromium.org/1639133003

Cr-Commit-Position: refs/heads/master@{#372035}
3 files changed